Tretoquinol impurities refer to any unwanted or unintended substances that may be present in tretoquinol, a medication used to treat heart conditions such as hypertension and angina. These impurities can be harmful to human health and may include contaminants, byproducts, or other unwanted substances that can affect the efficacy and safety of the medication. It is important to monitor and control the levels of tretoquinol impurities to ensure the medication is safe and effective for patients.